Conventionally, a plasma processing apparatus for performing plasma processing is widely used in a semiconductor manufacturing process such as etching, deposition, oxidation, sputtering or the like.
Generally, a capacitively coupled plasma processing apparatus has a configuration in which an upper electrode and a lower electrode are disposed in parallel to each other in a processing chamber configured as a vacuum chamber. In this configuration, a target substrate (a semiconductor wafer, a glass substrate or the like) is mounted on the lower electrode and a high frequency is applied to one of the electrodes. As a consequence, electrons accelerated by a high frequency electric field generated between both electrodes, secondary electrons emitted from the electrodes, or heated electrons are made to collide with and ionize molecules of a processing gas. As a result, a plasma of the processing gas is generated and a desired fine processing, e.g., an etching process, is performed on a surface of the substrate by radicals or ions in the plasma. In the etching process, there is widely used a dual frequency application type in which a first high frequency power having a relatively high frequency (typically, about 40 MHz or above) for plasma generation (discharge) is applied to the upper electrode or the lower electrode and a second high frequency power having a relatively low frequency (typically about 13.56 MHz or less) for ion attraction to a substrate is applied to the lower electrode. In addition, in the capacitively coupled plasma processing apparatus, there is employed a type in which a plasma is generated between both electrodes by the above-described high frequency discharge and a DC voltage is applied to the upper electrode facing the substrate across the plasma (see, Japanese Patent Application Publication Nos. 2010-251752 and 2011-521472, Japanese Utility Model Registration No. 3167751).
There is proposed a cam lock for mechanically attaching the upper electrode to a receiving plate in the above plasma processing apparatus. In the proposed mechanism, a stud that is press-fitted to a socket above the electrode is engaged with a cam shaft surrounded by a cam bearing in the receiving plate. The cam lock is realized by rotating the cam shaft through an opening formed at an outer peripheral surface of the receiving plate.
However, in such a mechanism, it is difficult to finely control a lifting force of the upper electrode.